Long-term plastic changes in the brain, including those supporting memory formation, are assumed to depend on permanent functional alterations in neuronal cells that require reprogramming of gene expression. Inducible transcription factors encoded by immediate early genes such as c-fos, c-jun, jun-B and zif/268 (also known as krox-24, egr-1, TIS 8, NGFI-A or zenk) are supposed to act as messengers in coupling short-term neuronal activity with changes at the level of gene transcription. This review will summarize studies on the expression of transcription factor-encoding immediate early genes in the vertebrate brain during behavioral training. Special emphasis will be given to correlative or interventive experimental evidence indicative of a physiological significance of inducible transcription factors for processes underlying learning and memory formation.